Blanking die stripping system

ABSTRACT

A pair of opposed blanking die members for blanking sheet metal parts having a fluid supply conduit for supplying fluid under pressure to the die cavity for ejecting the blanked part therefrom and a fluid actuated stripper ring reciprocably mounted on the blanking punch for ejecting the sheet metal skeleton therefrom.

United States Patent 1191 Plumb 1 51 May 15,1973

[76] Inventor:

[54] BLANKING DIE STRIPPING SYSTEM Edwin W. Plumb, Linden Road, Woodbury, Conn. 06792 [22] Filed: Mar. 22, 1971 [21] Appl. No.: 126,571

52 U.S.Cl. ..83/98,83/137,83/l67,

83/125 51 Int.Cl. ..B26d 7/00 58 FieldofSearch ..s3/9s,99,137,125,

[56] References Cited UNITED STATES PATENTS 2,579,940 Lobrovich ..83/l 37 X l2/l970 l/l950 Wingard ..83/99 X Urquhart ..83/167 Primary ExaminerAndrew R. Juhasz Assistant Examiner-W. Donald Bray A ttorney- Prutzman, Hayes, Kalb & Chilton [57] ABSTRACT A pair of opposed blanking die members for blanking sheet metal parts having a fluid supply conduit for supplying fluid under pressure to the die cavity for ejecting the blanked part therefrom and a fluid actuated stripper ring reciprocably mounted on the blanking punch for ejecting the sheet metal skeleton therefrom.

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ATTORNEYS 1 BLANKING DIE STRIPPING SYSTEM BRIEF SUMMARY OF THE INVENTION The present invention relates to blanking dies and more particularly to a stripping system for ejecting the blanked part from the die cavity and the sheet material skeleton from the blanking punch.

It is a principal aim of the present invention to provide a new and improved fluid stripping system employing fluid pressure for ejecting the blanked part from the die cavity and the sheet material skeleton from the blanking punch.

It is another aim of the present invention to provide a new and improved fluid actuated stripper for a blanking die.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

A better understanding of the invention will be obtained from the following detailed description and the accompanying drawings of an illustrative application of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is an isometric view, partly broken away and partly in section, showing a pair of blanking die members of a blanking die assembly incorporating an embodiment of the present invention; and

FIGS. 2-6 are transverse section views, partly broken away and partly in section, showing the sequence of operation of the blanking die assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail wherein like numerals are used to designate like parts throughout the several figures, a blanking die assembly 8 incorporating an embodiment of the present invention is shown comprising a first overlying female die member 10 and a second underlying male die member 12. The die members l0, 12 are to be suitably mounted in any wellknown manner for relative displacement toward and away from each other, for which purpose the die members are provided with openings 13 for receiving suitable mounting pins (not shown) for maintaining the die members 10, 12 in alignment while permitting relative displacement thereof between spaced relatively withdrawn positions shown in FIG. 2 and coacting relatively extended positions shown in FIG. 4 for blanking a sheet metal part 14 from a sheet stock strip 16.

The upper die member 10 has an inwardly facing die opening or cavity which is contoured in accordance with the peripheral contour of the desired blanked part,

and the lower die member 12 has a raised cutting surface provided by an inwardly projecting blanking punch I8 contoured in conformity with the die opening 20 for blanking out a sheet metal part 14 in a wellknown manner. The upper die member 10 also comprises integral inwardly projecting piercing punches 24-28 and the blanking punch 18 is provided with conforming piercing die openings -34 respectively for blanking holes in each sheet metal part 14. The lower die member 12 is also shown provided with outwardly tapered discharge passages for the piercing die openings 30-34 for discharging the pierced slugs from the die assembly.

Each of the die members l0, 12 may be of single piece construction as shown in the drawings and may be manufactured from heavy gauge stock by suitable machining operations and subsequent heat treatment as necessary.

In accordance with the present invention, the upper female die member 10 is provided with a fluid conduit 40 leading to the inside face 41 of the die cavity 20 for supplying fluid pressure to the die cavity for assisting in ejecting each blanked part 14 downwardly from the die cavity as the die members l0, 12 are withdrawn. Also, the lower male die member 12 is provided with a peripheral groove or channel 42 surrounding the punch 18 (and defined in part by a side wall of the blanking punch) and a fluid conduit 44 leading to the inside face 45 of the groove 42. The groove 42 preferably has a constant cross section with parallel side walls extending substantially parallel to the axis of relative movement of the die members 10, 12. A stripper ring 50 is provided in the peripheral groove 42 preferably by casting it in place using a low temperature metal, plastic, or urethane material, and so that the stripper ring 50 fits snugly within the groove 42 and is adapted to be actuated by fluid pressure inwardly toward the upper die member 10.

The conduits 40, 44 are preferably interconnected as shown in FIGS. 2-6 and a suitable pump 54 shown driven by a motor 56 is provided for supplying fluid under pressure to the conduits 40, 44. Suitable controls (not shown) are preferably provided for assuring temporary and timely supply of fluid under pressure to the conduits 40, 44 during the blanking operation. Also, a pressure gauge 58 connected to the fluid line is illustrated in the drawings to indicate the applied pressure at the several stages of the blanking operation shown in FIGS. 2-6. Although a pneumatic system could be used for supplying air to the conduits 40, 44, a liquid fluid is preferably used in which event the lubrication system conventionally employed for lubricating and cooling the dies during the blanking process may be used for supplying lubricant under pressure to the conduits 40,

Referring particularly to FIGS. 2-6, with the die members l0, 12 fully withdrawn (as shown in FIG. 2) the fluid passage 40 is connected to atmosphere and accordingly there is little or no fluid pressure in the fluid conduits 40, 44 even though there is some flow through the conduit 40 to the die cavity 20. As the die members l0, l2 engage the sheet metal stock 16 (as shown in FIG. 3), the die cavity 20 is closed by the sheet metal stock (for which pur ose the in r faces of the iercin P P g punches 24-28 are made substantially coplanar with the inner peripheral planar face 52 of the die member 10 and the inner planar face 53 of the, blanking punch 18 is made parallel with the inner planar face 52 of the die member 10) and the fluid pressure in the conduits 40, 44 thereupon begins to increase (as shown by the pressure gauge in FIG. 3) to bias the stripper ring 50 against the stock 16. Thus, with the die members in their fully extended relative positions shown in FIG. 4 (and the part 14 severed from the remaining sheet material stock), the stripper ring 50 biases the stock skeleton 60 against the inner face 52 of the die member 10 and the hydraulic pressure in the die cavity 20 biases the blanked part 14 against the inner face 53 of the blanking punch 18. As the die members 10, 12am withdrawn, the stripper ring 50 provides for stripping the stock skeleton 60, from the blanking punch 18 and the hydraulic fluid in the die cavity provides for ejecting the blanked part 14 from the die cavity 20. And as the die members 10, 12 become separated by an amount greater than the thickness of the sheet metal stock 16 and the blanked part 14 is ejected from the die cavity 20, the fluid pressure in the die cavity 20 is re lieved (and the fluid pressure acting on the stripper is .thereupon relieved) for inactivating the fluid ejection system. (in addition, the stripper ring 50 is mounted on the blanking punch 18 and the groove 42 is adapted to be connected to atmosphere before the stripper ring 50 could be hydraulically actuated off the blanking punch 18.) Where desired an additional stripper ring (not shown) could be mounted within a peripheral groove within the die cavity 20 and be fluid operated to eject the blanked part 14 from the die cavity 20 in the manner of the operation of the stripper ring 50.

As will be apparent to persons skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the teachings of the present invention.

I claim: 4

1. In a blanking die assembly having a pair of opposed die members with a first die member having an inner face with a die cavity therein and a second die member having a raised inner face providing a blanking punch, the blanking punch and die cavity providing cooperating parts for blanking parts from sheet material upon rectilinear relative movement of the diemembers between withdrawn relative positions and coacting relative positions, the improvement wherein the die assembly further comprises afluid stripping system comprising means for providing a source of pressure fluid, an inwardly opening stripper mounting cavity in one of the die members axially outwardly of said inner face thereof, a first fluid conduit for supplying the pressure fluid to the stripper mounting cavity, a stripper mounted within the stripper mounting cavity for rectilinear movement parallel to the axis of relative movement of the die members for being fluid pressed against the sheet material upon relative movement of the die members to their coacting relative positions and for being fluid actuated for stripping the sheet material from said one die member upon relative withdrawal of the die members, and a second fluid conduit having an outlet opening in one of the cooperating parts and connected to said first fluid conduit for automatically relieving the fluid pressure in the first fluid conduit when the second fluid conduit is connected to atmosphere upon the removal. of the sheet material from said one cooperating part.

2. A blanking die assembly according to claim 1 wherein the said one die member is the said second die member and wherein the stripper mounting cavity and stripper mounted therein extend at least in part around the blanking punch whereby the stripper is operable for being fluid actuated for stripping the sheet material from the blanking punch upon relative withdrawal of the die members.

3. A blanking dieassembly according to claim 2 wherein the stripper mounting cavity and stripper extend entirely around the blanking punch.

4. A blanking die assembly according to claim 3 wl erein the blanking punch has an axially extending side wall forming a side wall of the blanking punch and the stripper is reciprocably mounted on the blanking punch.

5. A blanking die assembly according to claim 2 wherein the second fluid conduit leads to the die cavity of the first die member for supplying the pressure fluid to the die cavity for ejecting blanked parts therefrom.

6. A blanking die assembly according to claim 5 wherein said inner faces of the first and second die members are substantially planar and parallel.

7. A blanking die assembly according to claim 6 wherein said first die member has at least one inwardly projecting piercing punch surrounded by the die cavity and having an inner planar face substantially coplanar with said inner planar face of the first die member and wherein said second die member has a piercing die opening therein cooperable with the piercing punch for piercing an opening in the blankedpart and whereby the pressure fluid in the die cavity provides for substantially fully ejecting the blanked part from both the die cavity and the piercing punch before the second fluid conduit is exhausted to atmosphere.

8. A blanking die assembly comprising a pair of opposed die members operable upon rectilinear relative movement thereof between withdrawn relative positions and coacting relative positions for blanking parts from sheet material stock, a first of the die members having an inwardly opening blanking die cavity, an inner planar face surrounding the die cavity, a first fluid conduit to the die cavity for supplying pressure fluid thereto for ejecting blanked parts therefrom upon relative withdrawal of the die members, and at least one inwardly projecting piercing punch having an inner planar face substantially coplanar with said inner planar face surrounding the die cavity, and a second of the die members having an inwardly projecting blanking punch adapted for coaction with the die cavity and having an inner planar face parallel to said inner coplanar faces of the first die member and an inwardly facing piercing die opening adapted for coaction with the piercing punch, an inwardly opening stripper mounting channel surrounding the blanking punch and spaced axially outwardly of the inner face thereof, a second fluid conduit leading to the channel, and a stripper ring mounted for rectilinear movement withinthe channel parallel to the relative movement of the die members for being fluid actuated inwardly to strip sheet material from the blanking punch upon withdrawal of the die members, the first and second fluid conduits being directly connected for automatically relieving the fluid pressure acting on the stripper ring upon the ejection of a blanked part from the die cavity. i

9. A blanking die assembly comprising a pair of opposed die members operable upon rectilinear relative movement thereof between withdrawn relative positions and coacting relative positions for blanking parts from sheet material stock, a first of the die members having an inwardly opening blanking die cavity, and a second of the die members having an inwardly projecting blanking punch adapted for coaction with the die cavity and an inwardly opening stripper mounting channel of substantially constant cross section surrounding the blanking punch and spaced axially outwardly of the inner end thereof, a fluid conduit leading to the mounting channel, and a stripper ring mounted for rectilinear movement within the channel parallel to the axis of relative movement of the die members for being fluid actuated inwardly to strip sheet material punch upon relative withdrawal of the die members and to be fluid actuated out of the mounting channel to relieve the pressure in the channel before the stripper can be fluid actuated axially off the blanking mounted on the blanking punch to be fluid actuated punch.

outwardly to strip the sheet material from the blanking 

1. In a blanking die assembly having a pair of opposed die members with a first die member having an inner face with a die cavity therein and a second die member having a raised inner face providing a blanking punch, the blanking punch and die cavity providing cooperating parts for blanking parts from sheet material upon rectilinear relative movement of the die members between withdrawn relative positions and coacting relative positions, the improvement wherein the die assembly further comprises a fluid stripping system comprising means for providing a source of pressure fluid, an inwardly opening stripper mounting cavity in one of the die members axially outwardly of said inner face thereof, a first fluid conduit for supplying the pressure fluid to the stripper mounting cavity, a stripper mounted within the stripper mounting cavity for rectilinear movement parallel to the axis of relative movement of the die members for being fluid pressed against the sheet material upon relative movement of the die members to their coacting relative positions and for being fluid actuated for stripping the sheet material from said one die member upon relative withdrawal of the die members, and a second fluid conduit having an outlet opening in one of the cooperating parts and connected to said first fluid conduit for automatically relieving the fluid pressure in the first fluid conduit when the second fluid conduit is connected to atmosphere upon the removal of the sheet material from said one cooperating part.
 2. A blanking die assembly according to claim 1 wherein the said one die member is the said second die member and wherein the stripper mounting cavity and stripper mounted therein extend at least in part around the blanking punch whereby the stripper is operable for being fluid actuated for stripping the sheet material from the blanking punch upon relative withdrawal of the die members.
 3. A blanking die assembly according to claim 2 wherein the stripper mounting cavity and stripper extend entirely around the blanking punch.
 4. A blanking die assembly according to claim 3 wherein the blanking punch has an axially extending side wall forming a side wall of the blanking punch and the stripper is reciprocably mounted on the blanking punch.
 5. A blanking die assembly according to claim 2 wherein the second fluid conduit leads to the die cavity of the first die member for supplying the pressure fluid to the die cavity for ejecting blanked parts therefrom.
 6. A blanking die assembly according to claim 5 wherein said inner faces of the first and second die members are substantially planar and parallel.
 7. A blanking die assembly according to claim 6 wherein said first die member has at least one inwardly projecting piercing punch surrounded by the die cavity and having an inner planar face substantially coplanar with said inner planar face of the first die member and wherein said second die member has a piercing die opening therein cooperable with the piercing punch for piercing an opening in the blanked part and whereby the pressure fluid in the die cavity provides for substantially fully ejecting the blanked part from both the die cavity and the piercing punch before the second fluid conduit is exhausted to atmosphere.
 8. A blanking die assembly comprising a pair of opposed die members operable upon rectilinear relative movement thereof between withdrawn relative positions and coacting relative positions for blanking parts from sheet material stock, a first of the die membeRs having an inwardly opening blanking die cavity, an inner planar face surrounding the die cavity, a first fluid conduit to the die cavity for supplying pressure fluid thereto for ejecting blanked parts therefrom upon relative withdrawal of the die members, and at least one inwardly projecting piercing punch having an inner planar face substantially coplanar with said inner planar face surrounding the die cavity, and a second of the die members having an inwardly projecting blanking punch adapted for coaction with the die cavity and having an inner planar face parallel to said inner coplanar faces of the first die member and an inwardly facing piercing die opening adapted for coaction with the piercing punch, an inwardly opening stripper mounting channel surrounding the blanking punch and spaced axially outwardly of the inner face thereof, a second fluid conduit leading to the channel, and a stripper ring mounted for rectilinear movement within the channel parallel to the relative movement of the die members for being fluid actuated inwardly to strip sheet material from the blanking punch upon withdrawal of the die members, the first and second fluid conduits being directly connected for automatically relieving the fluid pressure acting on the stripper ring upon the ejection of a blanked part from the die cavity.
 9. A blanking die assembly comprising a pair of opposed die members operable upon rectilinear relative movement thereof between withdrawn relative positions and coacting relative positions for blanking parts from sheet material stock, a first of the die members having an inwardly opening blanking die cavity, and a second of the die members having an inwardly projecting blanking punch adapted for coaction with the die cavity and an inwardly opening stripper mounting channel of substantially constant cross section surrounding the blanking punch and spaced axially outwardly of the inner end thereof, a fluid conduit leading to the mounting channel, and a stripper ring mounted for rectilinear movement within the channel parallel to the axis of relative movement of the die members for being fluid actuated inwardly to strip sheet material from the blanking punch upon withdrawal of the die members, the blanking punch having an axially extending side wall forming a side wall of the stripper mounting channel and the stripper being reciprocably mounted on the blanking punch to be fluid actuated outwardly to strip the sheet material from the blanking punch upon relative withdrawal of the die members and to be fluid actuated out of the mounting channel to relieve the pressure in the channel before the stripper can be fluid actuated axially off the blanking punch. 